With progressing monolithic integration of entire micro-electromechanical systems on one chip fabricated by standard IC technology we have to cope with the problem that the operation of embedded transducer elements is considerably affected by cross-coupling and parasitic effects. Referring to a BiCMOS-integrated capacitive pressure sensor as an illustrative example, we demonstrate that a detailed coupled-field analysis on the device level is indispensable to understand the interplay of various effects which contribute to the sensor output. On the basis of this analysis we are able to build a physically-based macromodel for the predictive simulation of the system performance.